I don't have a clothing policy but can certainly see why it would be beneficial!! For the most part, I have always had children sent in appropriate clothing and footwear but there is the odd parent or time that they have sent inappropriate stuff. I just discussed it when need be and resolved the problem. If I was finding that most of my group had this issue, I would just mention it in my monthly newsletters as well as talking to the parents in person so they understood my reasons. I'm about to write up my June newsletter and may make note of this. They all have running shoes for the most part though or the sandals with straps but you never know!!